Parse file name and path from full path

I do a lot of ETL work and I was looking for a function that I could use and qub1n's solution works very good except for values without a back slash. Here is a little tweak of qub1n's solution that will handle strings without back slashes:

Create FUNCTION fnGetFileName
(
    @fullpath nvarchar(260)
) 
RETURNS nvarchar(260)
AS
BEGIN
    IF(CHARINDEX('\', @fullpath) > 0)
       SELECT @fullpath = RIGHT(@fullpath, CHARINDEX('\', REVERSE(@fullpath)) -1)
       RETURN @fullpath
END

Samples:

    SELECT [dbo].[fnGetFileName]('C:\Test\New Text Document.txt') --> New Text Document.txt
    SELECT [dbo].[fnGetFileName]('C:\Test\Text Docs\New Text Document.txt') --> New Text Document.txt
    SELECT [dbo].[fnGetFileName]('New Text Document.txt') --> New Text Document.txt
    SELECT [dbo].[fnGetFileName]('\SERVER\D$\EXPORTFILES\EXPORT001.csv') --> EXPORT001.csv

Here is a LINK to SqlFiddle

Here is the simplest way

DECLARE @full_path VARCHAR(1000)
SET @full_path = '\\SERVER\D$\EXPORTFILES\EXPORT001.csv'
SELECT  LEFT(@full_path, LEN(@full_path) - CHARINDEX('\', REVERSE(@full_path)) - 1),
        RIGHT(@full_path, CHARINDEX('\', REVERSE(@full_path)) - 1)

Answer based on comment by Stefan Steiger:

Create FUNCTION GetFileName
(
 @fullpath nvarchar(260)
) 
RETURNS nvarchar(260)
AS
BEGIN
DECLARE @charIndexResult int
SET @charIndexResult = CHARINDEX('\', REVERSE(@fullpath))

IF @charIndexResult = 0
    RETURN NULL 

RETURN RIGHT(@fullpath, @charIndexResult -1)
END
GO

Test code:

DECLARE @fn nvarchar(260)

EXEC @fn = dbo.GetFileName 'AppData\goto\image.jpg'
PRINT @fn -- prints image.jpg

EXEC @fn = dbo.GetFileName 'c:\AppData\goto\image.jpg'
PRINT @fn -- prints image.jpg

EXEC @fn = dbo.GetFileName 'image.jpg'
PRINT @fn -- prints NULL

Use this -

DECLARE @full_path VARCHAR(1000)
SET @full_path = '\\SERVER\D$\EXPORTFILES\EXPORT001.csv'

SELECT LEFT(@full_path,LEN(@full_path) - charindex('\',reverse(@full_path),1) + 1) [path], 
       RIGHT(@full_path, CHARINDEX('\', REVERSE(@full_path)) -1)  [file_name]